Gridded Global Land Surface Precipitation Data based on in-situ raingauge observations.

[Text from: U. Schneider, T. Fuchs, A. Meyer-Christoffer, B. Rudolf: Global Precipitation Analysis Products of the GPCC, Global Precipitation Climatology Centre (GPCC), Deutscher Wetterdienst, Offenbach a. M., Germany, July 2008.]

The new Global Precipitation Climatology is focussing on the period 1951-2000 and consists of data from ca. 50,300 stations. The climatology comprises normals collected by WMO (CLINOs), delivered by the countries to GPCC or calculated from time-seriesof monthly data (with at least 10 complete years of data) available in our data base. In case that time series of sufficient length (more than 40 years) for the period 1951-2000 were not available from a specific station, then climatological normals have also been calculated for 30-year reference periods 1961-1990, 1951-1980 or 1971-2000 with at least 20 years of data. If even this was not possible for a station, then normals have been calculated for the period 1931-1960, or for any other period with at least 10 complete years of data.

The Monitoring Product of monthly precipitation for global climate monitoring is based on SYNOP and monthly CLIMAT reports received near-realtime via GTS from about 7,500 stations (after high level QC) and is available within about 2 months after observation month. This is the GPCC product with the longest history: Operational monthly analysis started with year 1986 and has continuously been done every month since then. The analyses are based on intensive automatic and manual quality control of the input data. The GPCC Monitoring Product is the in situ component to the satellite-gauge com-
bined precipitation analyses of GPCP (Huffman et al. 1995, Adler et al. 2003) and of CMAP (Xie and Arkin 1997). It also supports regional climate monitoring. Figure 3 illustrates a seasonal precipitation anomaly monitoring application for the region of Europe.

The Full Data Reanalysis Product is of much higher accuracy compared to the GPCC near real-time products mentioned above. Therefore, its application is recommended for hydrometeorological model verification and water cycle studies, e.g. in context of UNESCO, GEWEX, and GTN-H (Global Terrestrial Network for Hydrology). This analysis product is based on all stations, near real-time and non real-time, in the GPCC data base supplying data for the individual month. The GPCC Full Data Reanalysis Product Version 4 covers the period from 1901 to 2007 (see example in Figure 4); this new extended product version using the new GPCC climatology as analysis background is available since 25 September 2008. The data coverage per month varies from less than 10,000 to more than 45,000 stations (Figure 7). The full data re-analyses will be updated at irregular time intervals subsequent to significant data base improvements.

The VASClimO 50-Year Data Set supplying gridded time-series of monthly precipitation for climate variability and trend studies is based on data being selected with respect to a (mostly) complete temporal data coverage and homogeneity of the time-series. The current version 1.1 is based on time-series of 9,343 stations covering the period 1951-2000 (Beck, Grieser and Rudolf, 2005). These long-term climatological analyses of homogenised area-averaged precipitation time-series are of special interest for GCOS and supported the Intergovernmental Panel on Climate Change (IPCC) Working Group I Fourth
Assessment Report (FAR), published in year 2007. Figure 5 shows an application example: Linear trends of annual total precipitation for 1951-2000. The VASClimO Data Set will be updated at irregular time intervals subsequent to significant data base improvements; in Spring 2009 a new Version 2 for period 1951-2005 will become available.